Trust me, passive jammers are garbage.
There's no "magic bullet" in (legally) avoiding radar traps. All you can do is drive smart, keep your eyes peels, and don't attact attention to yourself.
One of my favorite tactics is to find someone in the hammer lane who's going the speed I want to go. I pace them in the center lane, about half a car length behind. If we come up on a radar trap -- and my Passport 8500 gives plenty of warning -- I simply slow down, and to the cop, it looks like I'm going 5 over the limit and being passed by someone going 20 over the limit.
It works like a charm, every time. If you want to be a jerk, too, you can sit in their blind spot and prevent them from changing lanes.
If you want to avoid them illegally, build an active radar jammer...just be prepared to answer to the FCC if/when you're caught. The FCC is an organization with which not to f***, so be careful.